The present invention relates generally to optical spectrometer systems, and more particularly, to an optical spectrometer system that employs a two-dimensional curved slit body surrounding an imaging slit that minimizes reflected background energy impinging upon a detector of the system.
Prior art relating to the present invention includes dispersive optical infrared spectrometers that use either prisms or gratings, for example. Typically, in a dispersive optical system having a detector and an imaging slit onto which the detector is focussed, and which is designed to operate within the infrared region of the optical spectrum, the imaging slit is cooled to minimize background effects caused by the system, and to reduce the background observed by the detector, either caused by transmitted or reflected energy. Cooling requires that the slit be placed in a vacuum dewar that is connected to a cryogen source, both of which are expensive.
Prior systems typically cool both the focal plane (detector) and the slit. In some systems, two vacuum dewars or one complex dewar incorporating the slit and the focal plane have typically been used. In other systems, one large or two smaller cryogenic coolers have been used to cool slit and focal plane. Furthermore, special materials and designs have also been required to maintain system alignment from room temperature down to operational temperature.
For example, prior systems have used a low reflectivity, high emissivity, flat slit surround that introduces a small percentage of the radiation from cavity wall. However, all of the in-field radiation from the slit surround plus the wall contribution is imaged at the focal plane. Another prior an system uses a high reflectivity, low emissivity flat slit surround or body that reduces the radiation from the slit surround and increases the contribution from the cavity walls. These two embodiments require that the slit surround or body and the cavity walls be cooled to minimize background effects.
In view of the above, it would be desirable to have a low emissivity slit body that surrounds an imaging slit that minimizes background energy received by the detector. It is therefore an objective of the present invention to provide for an optical imaging system that employs a two-dimensional curved slit body surrounding a spectrometer slit that minimizes reflected background energy impinging upon a detector of the system.